1. Field of the Invention 
The present invention relates generally to motor vehicles and, more particularly, to a trailer hitch cover assembly for a motor vehicle. 
2. Description of the Related Art 
It is known that motor vehicles may be provided with a trailer hitch to pull a trailer. Typically, the motor vehicle has a trailer hitch having a hitch tube secured to the motor vehicle beneath the bumper and a ball connector having an insert tube disposed in the hitch tube. A locking pin extends through the tubes to secure the insert tube to the hitch tube. The trailer generally includes a tongue beam, which is releasibly attached to the ball connector as is known in the art. 
Of concern in the use of the trailer hitch is the strength and cleanliness of the hitch tube. Typically, the trailer hitch, whether it is a ball or other type of attachment, has the insert tube and ball connector removed from the hitch tube and stored separately. This protects the ball connector and insert tube from corrosion and exposure to the atmosphere but leaves the hitch tube open to the same. The hitch tube, although constructed of metal and painted, being constantly exposed to the elements, will typically rust not only externally, but also within the interior of the hitch tube. Additionally, the hitch tube has a tendency to  collect mud and dirt from either off-road use or just daily driving. The result is that the hitch tube will have a build up of dirt and rust that will not only impair the insertion of the insert tube but also will ultimately weaken the entire hitch. Accordingly, there is a need in the art to protect the hitch tube by covering the opening of the hitch tube. 
There do exist “hitch covers” that are inserted into the end of the hitch tube to offer some protection, but they have certain drawbacks. These types of hitch covers often have more of a decorative purpose than one of protection for the hitch tube and they must be fully removed when the hitch is in use, thereby making them easy to misplace or lose. These types of hitch covers are also of a simple slide-in attachment and are susceptible to falling off or out during motor vehicle use without the driver's knowledge, returning to the original problem of exposing the hitch tube to the elements. Quite often these conventional decorative hitch covers have some sort of socially desirable design, such as a sports team emblem or the logo of the vehicle manufacturer, which make them targets of thieves, which again, if stolen, leaves the hitch tube exposed. 
Recently, vehicle manufactures have produced vehicles with the hitch tube extending through the bumper beam. The bumper beam is typically covered with a bumper fascia and an aperture is made in the bumper fascia surrounding the hitch tube to expose the hitch tube. As such, the hitch tube is exposed to the elements and the aperture in the bumper beam is unsightly and undesired. 